Fuel rail crossover hose

ABSTRACT

A fuel rail assembly with crossover conduits for communicating fuel between two fuel rails of a fuel-injected, spark ignited internal combustion engine is provided. The hose has a body with a mechanism for damping pressure pulsations within the fuel rail assembly.

FIELD OF THE INVENTION

The field of the present invention is fuel rail assemblies forspark-ignited reciprocating piston internal combustion engines and inparticular, fuel rail assemblies having crossover conduits such as tubesor hoses to allow fluid communication between two separate fuel railsfor reciprocating piston, spark-ignited internal combustion engines.

BACKGROUND OF THE INVENTION

In the past three decades, there have been major technological effortsto increase the fuel efficiency of automotive vehicles. One technicaltrend to improve fuel efficiency has been to reduce the overall weightof the vehicle. A second trend to improve fuel efficiency has been toimprove the aerodynamic design of a vehicle to lower its aerodynamicdrag. Still another trend is to address the overall fuel efficiency ofthe engine.

Prior to 1970, the majority of production vehicles with a reciprocatingpiston gasoline engine had a carburetor fuel supply system in whichgasoline is delivered via the engine throttle body and is thereforemixed with the incoming air. Accordingly, the amount of fuel deliveredto any one cylinder is a function of the incoming air delivered to agiven cylinder. Airflow into a cylinder is effected by many variablesincluding the flow dynamics of the intake manifold and the flow dynamicsof the exhaust system.

To increase fuel efficiency and to better control exhaust emissions,many vehicle manufacturers went to port fuel injection systems, wherethe carburetor was replaced by a fuel injector that injected the fuelinto a port which typically served a plurality of cylinders. Althoughport fuel injection is an improvement over the prior carburetor fuelinjection system, it is still desirable to further improve the controlof fuel delivered to a given cylinder. In a step to further enhance fueldelivery, many spark ignited gasoline engines have gone to a systemwherein there is supplied a fuel injector for each individual cylinder.The fuel injectors receive their fuel from a fuel rail, which istypically connected with all or half of the fuel injectors on one bankof an engine. Inline 4, 5 and 6 cylinder engines typically have onebank. V-block type 6, 8, 10 and 12 cylinder engines have two banks.

One critical aspect of a fuel rail application is the delivery of aprecise amount of fuel at a precise pressure. In an actual application,the fuel is delivered to the rail from the fuel pump in the vehicle fueltank. At an engine off condition, the pressure within the fuel rail istypically 45 to 60 psi. When the engine is started, a typical injectorfiring of 2–50 milligrams per pulse momentarily depletes the fuellocally in the fuel rail. Then the sudden closing of the injectorcreates a pressure pulse back into the fuel rail. The injectors willtypically be open 1.5–20 milliseconds within a period of 10–100milliseconds.

The opening and closing of the injectors creates pressure pulsations(typically 4–10 psi peak-to-peak) up and down the fuel rail, resultingin an undesirable condition where the pressure locally at a giveninjector may be higher or lower than the injector is ordinarilycalibrated to. If the pressure adjacent to the injector within the fuelrail is outside a given calibrated range, then the fuel delivered uponthe next opening of the injector may be higher or lower than thatpreferred. Pulsations are also undesirable in that they can cause noisegeneration. Pressure pulsations can be exaggerated in a returnlessdelivery system where there is a single feed into the fuel rail and thefuel rail has a closed end point.

To reduce undesired pulsations within the fuel rails, many fuel railsare provided with added pressure dampeners. Dampers with elastomericdiaphragms can reduce peak-to-peak pulsations to approximately 1–3 psi.However, added pressure dampeners are sometimes undesirable in that theyadd extra expense to the fuel rail and also provide additional leakpaths in their connection with the fuel rail or leak paths due to theconstruction of the damper. This is especially true with newEnvironmental Protection Agency hydrocarbon permeation standards, whichare difficult to satisfy with standard O-ring joints and materials. Itis desirable to provide a fuel rail wherein pressure pulsations arereduced while minimizing the need for dampers.

SUMMARY OF THE INVENTION

The present invention relates to a crossover conduit such as a tube orhose which connects fuel rails on a spark-ignited internal combustionengine. In one preferred embodiment, the crossover hose has a flattenedsection to improve flexibility and thereby reduce pressure pulsations inthe fuel rail assembly. The present invention provides a fuel rail whichprovides damping characteristics which minimizes or eliminates anyrequirement for separate fluid dampeners to be added to the fuel rail.

Further features and advantages of the present invention will becomemore apparent to those skilled in the art after a review of theinvention as it shown in the accompanying drawings and detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top schematic view of a fuel system which utilizes acrossover hose according to the present invention.

FIG. 2 is a side elevational schematic view of the crossover hose shownin FIG. 1.

FIG. 3 is a view taken along line 3—3 of FIG. 1.

FIG. 4 is a view taken along line 4—4 of FIG. 7.

FIG. 5 is a view taken along line 5—5 of FIG. 7.

FIG. 6 is a side elevational schematic view of an alternate preferredembodiment fuel crossover hose shown in FIG. 7.

FIG. 7 is a top schematic view of a fuel rail system utilizing analternate preferred embodiment crossover hose of the present invention.

FIG. 8 is a view taken along line 8—8 of FIG. 1.

FIG. 9 is a top schematic view of a fuel delivery system which utilizestwo separate crossover hoses.

FIG. 10 is a top schematic view illustrating a crossover hose similar ornear identical to that shown in FIGS. 7 and 9, and which additionallyincorporates a fluid flow restrictor.

FIG. 11 is a top schematic view of a crossover hose similar or nearidentical to that shown in FIGS. 1 and 9, and which additionallyincorporates a fluid flow restrictor.

FIG. 12 is a top partial schematic view of a fuel rail system whichutilizes a crossover hose wherein the hose end fittings incorporate afluid flow restrictor.

FIG. 13 is a schematic view of a fuel rail system which utilizes atleast one metallic crossover tube wherein the end fittings incorporate afluid flow restrictor mounted therein.

FIG. 14 is a schematic view of a fuel rail system which utilizes atleast one crossover tube wherein each of the end fittings incorporates afluid flow restrictor mounted therein.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 through 8, a fuel rail assembly 7 is providedaccording to the present invention. The fuel rail assembly includes afirst rail 10 and a second rail 12. Fuel rail 10 is provided with aninlet 13. The inlet 13 allows the fuel rail 10 to receive pressurizedfuel from a fuel pump (not shown). The fuel rail 10 has a control volume14, as provided by a generally rectangular tube 16. In other embodiments(not shown), the fuel rail may be a cylindrical tubular member. The fuelrail is typically made from sheet metal or a high-temperature tolerantpolymeric plastic material.

The fuel rail has a series of outlets or orifices 18. Flexibly joined tothe fuel rail adjacent to orifices 18 are injector cups 20. The injectorcups 20 provide an aligning and mounting surface for fuel injectors (notshown). As shown, fuel rail 10 has three orifices 18 and supplies fuelto a bank on a V6 internal combustion engine (not shown). The fuel rail10 has an orifice outlet which is provided with a connecting barbed maleneck fitting 24. The fuel rail 12 is essentially similar to the fuelrail 10, with the exception that it does not have an inlet which isconnected with the fuel pump.

To provide fluid communication for the fuel between the fuel rails 10and 12, there is a crossover conduit provided by a hose 30. The hose 30will typically have a structural portion wall thickness between 0.70 and1.4 mm. The crossover hose 30 structural portion is preferablyfabricated from a polymeric plastic material such as nylon/ETFE(copolymer of ethylene and tetrafluoroethylene) or other suitablealternatives. The crossover hose 30 has a 0.15 mm barrier layer formedof a fluoropolymer film such as that offered under the trademark TEFZEL®(copolymer of tetrafluoroethylene and ethylene) and an outside firejacket which is typically formed of a thermoplastic elastomer materialsuch as that offered under the trademark SANTOPRENE® or other fireresistant material such as the olefin alloy offered under the trademarkETHAVIN™ which can be 1.0–4.0 mm thick depending on burn testrequirements. The technical specification of the hose will often beSociety of Automotive Engineers' J 2045.

The crossover hose 30 has on its opposite ends female connections 34 toallow the crossover hose 30 to be joined with the fuel rails 10 and 12.The crossover hose, as shown, has a main body with a U shape, havingnon-flattened legs 36 and 38 which arc continuous with the endconnections 24 and 34. The legs 36 and 38 have a generally enlargeddiameter with respect to the diameter of the end connections 24, 34. Thebase of the channel shape provided by the crossover hose 30 has agenerally flattened portion 40. Legs 36 and 38 juxtapose the flattenedportion 40 from the end connections 24, 34. The flattened portion 40 hasa width 42 which is generally larger than the diameter 44 of the endconnections 34. In many instances it will be a 2:1 ratio over thediameter 44. The flattened portion 40 typically has a height 48 which isgreater than the diameter 44 of the end connections 34.

In operation, pressurized fuel will be delivered to fuel rail 10 throughinlet 13. Via inlet 13, fuel will be distributed to various injectors onone bank of a V6 engine via the orifices 18. Excessive fuel isdeliberately pumped into fuel rail 10 so as to communicate with the fuelrail 12 via the crossover hose 30. Fuel rail 12 will supply fuel to theopposite bank of the V6 engine in a manner similar to fuel rail 10.

The opening and closing of the various fuel injectors will causepulsations to be generated within the fuel rail assembly 7. Pulsationswill be absorbed by the flattened portion 40 of the crossover hose beingelastically deformed thereby. Increased pressurization will cause theflattened portion to expand in an attempt to take on a more circularshape. An enlarged volume will be created, thereby decreasing pressure.Under-pressurization will cause the degenerative flattened portion tocollapse, thereby reducing the overall volume within the crossover hoseand therefore inhibiting the decreasing pressure by reducing the overallvolume of the fuel rail assembly 7. The main damping effect is providedby the structural portion of the crossover hose 30.

Referring now to FIGS. 4 through 7, an alternate preferred embodimentfuel rail assembly 57 is provided having fuel rails 10 and 12 identicalas those previously described. The crossover hose 60 has two female endconnections 64 which are fitted over the neck orifices 24 of the fuelhose. The crossover hose 60 has a flattened portion 62 which has a widthwhich is significantly enlarged from that of the remainder of thecrossover hose. Pressure pulsations are minimized by the expansion andcontraction of the flattened portion in a manner as similarly describedfor the crossover hose 30.

It will be apparent to those skilled in art that male end connectionscan be substituted for the female end connection 64, if so desired.Typically, the height of the flattened portion 62 of the crossover hose60 will be less than the height of a crossover hose taken alongsectional line 5—5.

Referring to FIG. 9, a fuel rail delivery system 107 is provided havinga first fuel rail 110 and a second fuel rail 120. The fuel rail system107 has a fuel inlet 113 which delivers fuel through the top of the fuelrail 110. The fuel rails 110 and 120 also have a second set of orificeoutlets 125. Connected with the second set of orifice outlets 125 is asecond crossover hose 160. The second crossover hose 160 can have aflattened portion 162 as shown or it can simply be regular constantdiameter hose tubing. As readily apparent, crossover hose 160 and theopposite crossover hose 130 are non-symmetric with respect to oneanother. This helps to break up any resonant frequencies which may occurduring operation of the engine that the fuel delivery system 107 isassociated therewith.

Referring to FIGS. 10–11, a crossover hose 260 with a flattened portion262 is provided which is substantially similar to crossover hoses 160and 60 as previously described. Additionally, crossover hose 260 has afluid flow restrictor 267. Crossover hose 260 can be utilized in a fueldelivery system as described in FIG. 9 opposite a crossover hose 160.The fluid restrictor 267 and the crossover hose 260 provide a fluid flowrestrictor which makes the crossover hose 260 non-symmetric with respectto the crossover hose 160. As previously explained, the non-symmetricproperties will inhibit resonating vibrations from being generated.

In a similar manner, crossover hose 230 can be utilized in the fueldelivery system 113 with a crossover hose 130. If the body of acrossover hose 230 is identical with that of crossover hose 130, thenon-symmetric feature can be provided with a fluid flow restrictor 237provided in the crossover hose 230. The utilization of multiplecrossover hoses in fuel delivery system 113 provides even more evencross flow and also gives a more equal temperature distribution sincethere are no dead end legs for the fuel delivery system.

Referring to FIG. 12, a partial view of a fuel rail assembly 307, whichhas two fuel rails (only one shown) includes a fuel rail 308 having abarbed male fitting 310. The fitting 310 has a fluid flow restrictor 312mounted therein. The restrictor 312 reduces pulsations and evens theflow between the two fuel rails of the fuel rail assembly. In the fuelrail assembly 307, either a single or multiple fuel hoses 316 can beutilized.

Referring to FIG. 13, 1 fuel rail assembly 407 has fuel rails 410 and420 which are substantially similar to that of the fuel railsaforedescribed. Each of the fuel rails 410 and 420 has a fluid endconnection 414 which is joined to a metallic conduit provided by a tube416. The tube 416 would typically be brazingly connected with the endfitting 414. A fluid flow restrictor 412 is provided within the fitting414 which is connected with the fuel rail 410. A single fluid restrictor412 may be utilized or fluid restrictors of differing resistance or thesame may be utilized in both fittings 414 and the fuel rails 410 and 420(see FIG. 14).

It will be apparent to those skilled in the art that the fuel railassemblies 307 and 407 may have dual crossover conduits or single ones.

The present invention has been shown in several embodiments. However, itwill be apparent to those skilled in art of the various changes andmodifications which can be made to the present invention withoutdeparting from the spirit or scope of the invention as it has beenexplained and as embodied in the accompanying claims.

1. A fuel rail assembly for a fuel-injected spark-ignited internalcombustion engine comprising: first and second fuel rails, each saidfuel rail formed by a tube having a plurality of injector outlets, saidfirst and second fuel rails comprising a first set of orifice outletslocated at respective first ends of said rails and a second set oforifice outlets located at respective second ends of said fuel railsopposite said first ends, and one of said first and second fuel railscomprising a fuel inlet different from and located away from said firstand second sets of orifice outlets, said fuel inlet being locatedintermediate said first and second ends of said one rail, said fuelinlet configured for receiving pressurized fuel directly from a lowpressure fuel pump wherein said fuel has a pressure less than about 60psi; first and second crossover conduits for communicating fuel betweensaid fuel rails, said first crossover conduit located between said firstset of orifice outlets of said first and second fuel rails, and saidsecond crossover conduit located between said second set of orificeoutlets opposite said first crossover conduit; and one of said first andsecond crossover conduits having at least one fluid flow restrictor atone of said crossover conduit connections for damping pressurepulsations within said rails and to balance flow therebetween and theother one of said first and second crossover conduits having an absenceof said fluid flow restrictor.
 2. A fuel rail assembly as described inclaim 1 wherein said fuel rails are parallel spaced from one another. 3.A fuel rail assembly as described in claim 1 wherein each of said firstand second fuel rails has at least two separate orifices to allow forfluid communication of fuel between said fuel rails and wherein saidfirst and second crossover conduits are connected to said first andsecond fuel rails at opposite ends of said fuel rails.
 4. A fuel railassembly as described in claim 1 wherein said first and second crossoverconduits are non-symmetric with one another.
 5. A fuel assembly asdescribed in claim 1 wherein connector fittings join said fuel railswith said first and second crossover conduits.
 6. A fuel assembly asdescribed in claim 5 wherein at least one of said connector fittings isconnected with said at least one fluid flow restrictor.
 7. A fuelassembly as described in claim 5 wherein said connector fittings aremale barbed members and said crossover conduits are polymeric hoses. 8.A fuel assembly as described in claim 6 wherein said connector fittingsare male barbed members and said crossover conduits are polymeric hoses.9. A fuel assembly as described in claim 1 wherein one of said crossoverconduits has a fluid flow restrictor at both end connections with saidfuel rails.
 10. A fuel rail assembly as described in claim 1 whereinsaid pressurized fuel is low pressure fuel on the order of 45–60 psi.